diff --git a/libultraship/src/resource/archive/OtrArchive.h b/libultraship/src/resource/archive/OtrArchive.h
index 7979e058..45142b1f 100644
--- a/libultraship/src/resource/archive/OtrArchive.h
+++ b/libultraship/src/resource/archive/OtrArchive.h
@@ -1,4 +1,5 @@
 #ifndef EXCLUDE_MPQ_SUPPORT
+#define OTR_ARCHIVE_INCLUDED
 
 #pragma once